Make sure you have all the patches first. (I'm just going to assume anyone playing WC3 already does have the patches, so this doesn't really apply in this case.)

Check Blizzards FAQS and tech sections for references to what you've posted.

Try un-installing and then re-installing the game. If it still doesn't work, note the error, if it's coming up with the same memory address all the time your RAM could be wonky, in which case you'll want to have it tested.

A+ Certified PC Tech Guy/Seitentaisei